Explaining Audio Codecs

[rogue_nine82]

All,

I am utterly lost when it comes to explaining audio codecs. Which are the best, which is slated for 5.1, 6.1 or 7.1 sound? Is DTS-HD better than uncompressed PCM? Where does Dolby digital fit into all of this? What does uncompressed PCM at 48kbs mean anyhow?

Sorry if I screwed up the nomenclature but I am totally lost.

[HDorby]

You're not the only one.. I am just trying to get my hands on a Onkyo TX-SR605 here in canada, and I personnaly think it won't matter any more cause my hardware will be able to do it all

[GamerGuyX]

All,

I am utterly lost when it comes to explaining audio codecs. Which are the best, which is slated for 5.1, 6.1 or 7.1 sound? Is DTS-HD better than uncompressed PCM? Where does Dolby digital fit into all of this? What does uncompressed PCM at 48kbs mean anyhow?

Sorry if I screwed up the nomenclature but I am totally lost.

http://www.highdefdigest.com/news/sh...Explained/1064

[jeffreybehr]

Well, I'll start and others I'm sure will correct and expand.

1. PCM means pulse-code modulation, and what that means to movie lovers is that the encoding used on the soundtrack is NOT compressed to take up less space. PCM is a bit-for-bit copy of the movie's master audio. The resolution of PCM audio can be as low as that on a CD, which is sampled 44.1-thousand times per second (abbreviated KHz) and uses digital words that are 16 bits long. That's abbreviated 44.1/16 or 44/16. Higher-resolution sampling rates include 48-, 88.2-, and 96KHz. Usually the word length is lengthened to 24 bits with these higher sampling rates, and some audiofools* believe that the additional dynamic range resulting from the use of 24 bits is more important for sound quality than the use of higher sampling rates.

For my money, 5.1-channel 48/24 PCM is as good as movie soundtracks need to be.

2. Dolby Digital and DTS (Digital Theater Systems) are methods to compress digital soundtracks so that they require less room on discs. This was necessary with DVDs because they were limited in capacity. DD compresses the most and loses the most fidelity (altho some believe these losses are hardly audible) and DTS less so. DD+ is less compressed than DD and is used on lots of HD DVDs. All 3 of these systems are 'lossy', which means that some of the original information is lost in the compression process and never recovered.

3. DolbyTrueHD and DTS Master Lossless Audio are higher-resolution methods of encoding digital sountracks that apparently require less space than PCM. I believe each claims to be nonlossy.

The May issue of the usually-worthless 'Home Theater' magazine has a very good explanation of these beginning on p. 36.
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* I've been one for almost 50 years, so I'm qualified to use that term.
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...and now I see that the same person who wrote the linked explanations wrote the article in 'Home Theater'.

[rogue_nine82]

Thanx everyone this has helped out a bunch.

[SLARITY]

Ya so if you can use PCM (uncompressed) or Dolby TrueHD or DTS-HDMA, those are the best and should all be identical.

[GamerGuyX]

Ya so if you can use PCM (uncompressed) or Dolby TrueHD or DTS-HDMA, those are the best and should all be identical.

Assuming the bit depth and sampling rate are equal...